Year | Value | 2021 | 28.02119460501 | 2020 | 28.02119460501 | 2019 | 28.02119460501 | 2018 | 28.02119460501 | 2017 | 28.02119460501 | 2016 | 28.731257208766 | 2015 | 28.95004803074 | 2014 | 29.686310324938 | 2013 | 30.285933601996 | 2012 | 29.394555973333 | 2011 | 31.079045132553 | 2010 | 31.792559188275 | 2009 | 32.375046974822 | 2008 | 32.963171739947 | 2007 | 33.568207440812 | 2006 | 34.144508127408 | 2005 | 34.498308906426 | 2004 | 34.827553801335 | 2003 | 35.263157894737 | 2002 | 35.698843876304 | 2001 | 34.813780260708 | 2000 | 32.625698324022 | 1999 | 33.612662942272 | 1998 | 33.277467411546 | 1997 | 33.780260707635 | 1996 | 32.448789571695 | 1995 | 34.301675977654 | 1994 | 34.320297951583 | 1993 | 33.798882681564 | 1992 | 33.28677839851 | 1991 | 31.983240223464 | 1990 | 31.573556797021 | 1989 | 31.666666666667 | 1988 | 31.47113594041 | 1987 | 31.005586592179 | 1986 | 30.260707635009 | 1985 | 29.497206703911 | 1984 | 28.929236499069 | 1983 | 28.864059590317 | 1982 | 28.398510242086 | 1981 | 27.932960893855 | 1980 | 27.746741154562 | 1979 | 27.737430167598 | 1978 | 28.268156424581 | 1977 | 28.221601489758 | 1976 | 28.184357541899 | 1975 | 26.722532588454 | 1974 | 24.543761638734 | 1973 | 25.921787709497 | 1972 | 24.301675977654 | 1971 | 21.201117318436 | 1970 | 21.508379888268 | 1969 | 18.091247672253 | 1968 | 18.128491620112 | 1967 | 15.763500931099 | 1966 | 14.441340782123 | 1965 | 15.083798882682 | 1964 | 16.405959031657 | 1963 | 14.823091247672 | 1962 | 14.013035381751 | 1961 | 13.500931098696 |
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